Deflection yoke and method of making



Nov. 19, 1963 H. J. WEBB 3,111,609

DEFLECTION YOKE AND METHOD OF MAKING Filed March 16, 1959 x INVENTOR HERBERT J. WEBB,

BY /ML HIS ATTORNEY.

United States Patent Ofi lice 3,1 I 1,609 Patented Nov. 19, 1963 3,111,609 DEFLECTION YOKE AND METHOD OF MAKING Herbert J. Webb, Fernwood, N.Y., assignor to General Electric Company, a corporation of New York Filed Mar. 16, 1959, Ser. No. 799,615 2 Claims. (Cl. 317-200) As is well known by those skilled in the art, deflection yokes for cathode ray tubes are usually comprised of a first pair of coils for controlling deflection in one direction and a second pair for controlling deflection in :a direction perpendicular to the first. The coils forming each pair are usually mounted on diametrically opposed sides of a form, in most cases one pair is on the inside of the form and the other on the outside. In order to avoid what is known as cross talk, i.e. the coupling of energy from one pair to the other, one pair of coils is held in a fixed position by the form and the other pair is rotated until the cross talk is minimized. Various methods have been used to hold the coils in position, but until this invention no inexpensive method has proven successful. For example, bees-Wax has been applied at various points but after a time, the wax loses its holding power so that the coils are free to rotate. Even one half degree of relative rotation can cause marked defects in the image formed by a television receiver.

Furthermore, the methods of fabrication heretofore used have been time consuming and have produced a high number of rejects, i.e. yokes that have to be readjusted, with the result that these prior methods are exceedingly expensive.

Accordingly, it is an object of this invention to provide a deflection yoke of such design that the relative rotation between the coils is virtually impossible.

Another object of this invention is to provide an improved less expensive method of manufacturing deflection yokes in which relative rotation of the coils is virtually impossible.

Briefly, the deflection yoke of this invention is such that the surface of the form adjacent to a coil conforms to the surface of the coil. Then when the coil is mounted in position it fits into the form and rotation is prevented. In order to make a deflection yoke of this construction, the coils are mounted on the form and adjusted for minimum cross talk in the usual manner. A low viscosity solvent for the material of which the form is made is allowed to flow between the coil and the form. The surface of the form is softened and the stresses existing in the coils force the outer layer of wires into the softened area. The softened surface is then hardened or cured by passing current through the coils.

The manner in which these objectives are attained in accordance with the principles of this invention will be more clearly understood after consideration of the following detailed discussion of the drawings in which:

FIGURE 1 is a longitudinal cross section of a deflection yoke showing the general arrangement of the yoke coils and the form,

FIGURE 2 is a transverse section of a deflection yoke taken at AA on FIGURE 1, but showing both sides of the yoke,

FIGURE 3 is an enlarged sectional view showing the outer windings of the coil and the adjacent surface of the form prior to the application of the solvent,

FIGURE 4 is an enlarged sectional view showing the outer winding of the coil and the adjacent surface of the form after the application of the solvent, and

FIGURE 5 shows the indentation made in the form by the outer turns of wire.

In FIGURE 1 one pair of deflection coils 2 is shown on the inside of a form 4, and :a second pair of coils 6 is shown on the outside. In FIGURE 2, it is seen that the form 4 has a cross section that is oval in shape and that the turns of the coils 2 are so distributed as to provide a substantially circular opening between them. The outer periphery of the coil 2 is slightly larger than the inside of the form 4, at least for a portion of their length, so that they press outwardly against it. By holding the form with its flared end in an upward direction, a low viscosity solvent for the material of which the form 4 is comprised can be applied to the inner surface of the form as at points 8. Thus applied the solvent can flow between the outer turns of the coils 2 that are nearest the form and the inner or adjacent surface 10 of the form. The outward pressure of the coils 2 causes the outer turns to make indentations in the inner surface of the form, as can be seen by a comparison of FIGURES 3 and 4. Current is then passed through the coils 2 so as to harden the inner surface of the form. These indentations do not prevent the coils 2 from being removed from the form, but they do prevent them from being rotated with respect thereto. FIGURE 5 shows the indentations in the coil form made by the coils 2. Mechanical means, such as cars 12 can be used to prevent the outer coils 6 from rotating with respect to the form. If desired, the ears 12 could be omitted and the coils 6 mounted in the same manner as the coils 2, but in general this is not necessary.

While I have illustrated a particular embodiment of my invention, it will of course be understood that I do not Wish to be limited thereto, since various modifications can be made and I contemplate by the appended claims to cover all such modifications as come within the true spirit and scope of my invention.

What I claim and desire to secure by Letters Patent of the United States is:

1. A deflection yoke having a form, at least one surface of which is made of homogeneous material, said form having a slightly oval cross section, a pair of coils, each of said coils being comprised of a plurality of closely packed turns of wire having side portions in which the wires are substantially parallel, said pair of coils being mounted in opposed relation on said form and oriented so that said side portions are parallel to the axis of said form, a portion of the said surface of said form having impressions made from the individual turns of wire of the side portions of said coils, the coils being oriented such that the individual turns of wire fit into their impressions with the coils being removable therefrom but with the impressions preventing the rotation of said coils about the axis of said form.

2. A method of positioning coils of a deflection yoke on a yoke coil form comprising the steps of positioning the coils on the yoke coil form for minimum cross talk, applying a solvent for the material of the form to at least a portion of the surface adjacent :a pair of the coils, and passing a current through the coils to harden the form.

(References on following page) References Cited in the file of this patent UNITED STATES PATENTS Gernsback Feb. 15, 1927 Majce Dec. 10, 1929 Kurath July 28, 193 Bowman-Manifold Feb. 15, 1938 Tolson Apr. 25, 1939 Webb Jan. 8, 1946 4 Grundmann Feb. 26, 1946 Combs Jan. 25, 1949 Morrison May 23, 1950 Wendzel July 14, 1953 Sickles et a1. Oct. 19, 1954 Hanlet Apr. 8, 1958 Hanlet Apr. 15, 1958 Jones Aug. 5, 1958 Whearley May 2, 196 1 

1. A DEFLECTION YOKE HAVING A FORM, AT LEAST ONE SURFACE OF WHICH IS MADE OF HOMOGENEOUS MATERIAL, SAID FORM HAVING A SLIGHTLY OVAL CROSS SECTION, A PAIR OF COILS, EACH OF SAID COILS BEING COMPRISED OF A PLURALITY OF CLOSELY PACKED TURNS OF WIRE HAVING SIDE PORTIONS IN WHICH THE WIRES ARE SUBSTANTIALLY PARALLEL, SAID PAIR OF COILS BEING MOUNTED IN OPPOSED RELATION ON SAID FORM AND ORIENTED SO THAT SAID SIDE PORTIONS ARE PARALLEL TO THE AXIS OF SAID FORM, A PORTION OF THE SAID SURFACE OF SAID FORM HAVING IMPRESSIONS MADE FROM THE INDIVIDUAL TURNS OF WIRE OF THE SIDE PORTIONS OF SAID COILS, THE COILS BEING ORIENTED SUCH THAT THE INDIVIDUAL TURNS OF WIRE FIT INTO THEIR IMPRESSIONS WITH THE COILS BEING REMOVABLE THEREFROM BUT WITH THE IMPRESSIONS PREVENTING THE ROTATION OF SAID COILS ABOUT THE AXIS OF SAID FORM.
 2. A METHOD OF POSITIONING COILS OF A DEFLECTION YOKE ON A YOKE COIL FORM COMPRISING THE STEPS OF POSITIONING THE COILS ON THE YOKE COIL FORM FOR MINIMUM CROSS TALK, APPLYING A SOLVENT FOR THE MATERIAL OF THE FORM TO AT LEAST A PORTION OF THE SURFACE ADJACENT A PAIR OF THE COILS, AND PASSING A CURRENT THROUGH THE COILS TO HARDEN THE FORM. 